Producing apparatus of film with through-holes

ABSTRACT

A method for producing a film with through-holes includes using an apparatus having a pair of stretching rollers which sandwich a film therebetween and stretch the film. The producing apparatus further includes a pair of punching rollers which sandwich the film therebetween and punch through-holes in the film. The stretching rollers and the punching rollers are disposed so that the film stretched by the stretching rollers are fed to the punching rollers. The method includes stretching the film by means of the stretching rollers and punching through-holes in the film.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a division of U.S. patent application Ser.No. 09/167,572, filed on Oct. 7, 1998, the content of which is expresslyincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] This invention relates to a producing apparatus and a producingmethod of a film with through-holes.

[0003] In order to make a thin film (for example, 0.03 to 0.08 mm inthick) with through-holes, a stretching apparatus and a punchingapparatus are generally used. A thicker plastic film is heated andstretched to a target thickness by means of a stretching apparatus.Then, through-holes are punched in the plastic film by means of thepunching apparatus.

[0004] However, since separate two apparatus (that is, the stretchingapparatus and the punching apparatus) are needed, the whole equipmentfor producing the film with through-holes is complicated. Further, sincethe conventional producing method necessities separate two processes(that is, the stretching process and the punching process), the wholeprocess for producing the film with through-holes is complicated.

SUMMARY OF THE INVENTION

[0005] It is therefore an object of the present invention to simplifythe whole equipment and whole process for producing the film withthrough-holes.

[0006] According to an aspect of the present invention, there isprovided a producing apparatus of a film with through-holes including(1) a pair of stretching rollers which sandwich a film therebetween andstretch the film, and (2) a pair of punching rollers at least one ofwhich has projections formed on an outer surface thereof, which sandwichthe film therebetween and punch through-holes in the film. Thestretching rollers and the punching rollers are disposed so that thefilm stretched by the stretching rollers are fed into the punchingrollers.

[0007] With such an arrangement, since the stretching of the film andthe punching of the through-holes are performed by substantially oneapparatus, the whole equipment for producing the film with through-holesbecomes simple.

[0008] In a particular arrangement, the film is made of shape memoryresin. The producing apparatus further includes a first heater whichheats the film to a temperature above the shape providing temperature.Above the shape providing temperature, the shape memory resin exhibits afluidized state. Thus, the film is easily deformed by the stretchingrollers. It is preferred that the first heater is mounted in at leastone of the stretching rollers.

[0009] Further, the producing apparatus includes a second heater whichheats the film to a temperature above the glass transition temperature.-Above the glass transition temperature (but below the shape providingtemperature), the shape memory resin exhibits a rubber state (that is,an elastic state). Thus, the through-holes can easily be formed in thefilm. It is preferred that the second heater is mounted in at least oneof the punching rollers.

[0010] Optionally, the producing apparatus further includes a coolingdevice provided between the punching rollers and the stretching rollers.The cooling device cools the film to a temperature below the shapeproviding temperature.

[0011] In a preferred embodiment, there is provided a method forproducing a film with through-holes using the above-described producingapparatus. The method includes the steps of (1) stretching the film bymeans of the stretching rollers, and (2) punching through-holes in thefilm in a state the film is stretched.

[0012] With such a method, since the since the stretching of the filmand the punching of the through-holes are performed in substantially onecontinuous process, the whole process of producing the film withthrough-holes becomes simple.

[0013] In case the film is made of shape memory resin, the film isheated to a temperature above a shape providing temperature of the shapememory resin, in the stretching step. Further, the film is heated to atemperature above a glass transition temperature of the shape memoryresin in the punching step. It is also possible to cool the film below ashape providing temperature of the shape memory resin, after thestretching step.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a perspective view of a film from which a film withthrough-holes is formed;

[0015]FIG. 2 is a schematic view of a producing apparatus according tothe embodiment of the present invention;

[0016]FIG. 3 is a diagram showing an example of a characteristic of ashape memory resin;

[0017]FIG. 4 is a sectional view of a ink transfer printer using thefilm produced by the producing method of FIG. 2;

[0018]FIG. 5 is an exploded perspective view showing a main part of theink transfer printer of FIG. 4; and

[0019]FIGS. 6A and 6B are schematic views illustrating ink transferringprocess of the ink transfer printer of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] The embodiment of the producing apparatus and method of a filmwith through-holes according to the present invention is describedbelow.

[0021]FIG. 1 is a perspective view of a film 20 from which a film withthrough-holes is produced. FIG. 2 is a schematic view showing aproducing apparatus of a film with through-holes according to the firstembodiment. The film 20 shown in FIG. 1 is made of shape memory resinand has a square shape, each side thereof having the length L. Thethickness t of the film 20 is from 1 to 4 mm. In FIG. 1, X-direction andY-direction are defined along two adjacent sides of the film 20.

[0022] The shape memory resin exhibits different characteristicsabove/below a glass transition temperature T_(g). FIG. 3 is a diagramshowing an example of the characteristics of the shape memory resin.When the shape memory resin is heated to a temperature above a glasstransition temperature T_(g) (and below a shape-providing temperatureT_(D) described below) as shown by “b” in FIG. 3, the shape memory resinexhibits a rubber state (that is, an elastic state), in, which Brownianmotion of molecules is activated. When the shape memory resin is cooledto a temperature below the glass transition temperature T_(g) as shownby “a” in FIG. 3, the shape memory resin exhibits a solid state in whichBrownian motion of molecules is frozen. Further, if the shape memoryresin is heated to a temperature above a shape-providing-temperature T₀as shown by “c” in FIG. 3, the shape memory resin exhibits a fluidizedstate in which molecules are fluidized. In this fluidized state, theshape memory resin is given an original shape.

[0023] Examples of the shape memory resin are as follows: (1)polynorbornene, (2) trans-1,4-polyisoprene, and (3) polyurethane. Ingeneral, the glass transition temperature T_(g) of the shape memoryresin is from 50 to 130 degree centigrade (° C.). In this embodiment,polyurethane resin (which is low cost and has excellent moldability) isused. Further, in this embodiment, the glass transition temperatureT_(g) of the shape memory resin is 60° C. The shape memory resin isdisclosed in Japanese Laid-Open Patent Application Nos. HEI 5-305666 andHEI 8-49960, teachings of which are incorporated herein by reference intheir entireties.

[0024] As shown in FIG. 2, a stretching roller pair 10 is provided forstretching the film 20, including the upper and lower rollers 11 and 12faced with each other. A punching roller pair 50 are provided forpunching through-holes in the film 20, including a needle roller 51 anda platen roller 52 faced with each other. The stretching roller pair 10and the punching roller pair 50 are disposed in parallel to each other.

[0025] The upper roller 11 of the stretching roller pair 10 is rotatedcounterclockwise, while the lower roller 12 is rotated clockwise. Theneedle roller 51 of the punching roller pair 50 is rotatedcounterclockwise, while the platen roller 52 is rotated clockwise. Thestretching roller pair 10 and the punching roller pair 50 are driven bya common driving mechanism 60 and rotated at the same circumferentialvelocity.

[0026] The film 20 is inserted in a gap between the stretching rollerpair 10 in Y-direction. The upper and lower rollers 11 and 12respectively have built-in heater 11 a and 12 a and heated at 150° C.,which is higher than the shape-providing temperature To of the shapememory resin of the film 20. The film 20 is heated so that the film 20exhibits a fluidized states and pressed by the stretching roller pair10, so that the film 20 is stretched in Y-direction. The film 20 isstretched so that the thickness of the film 20 is 0.03 to 0.08 mm(t/40). Since the film 20 is heated to a temperature above theshape-providing temperature T₀, the thickness (0.03 to 0.08 mm) of thefilm 20 is maintained after the applied head and pressure are removed.

[0027] A pair of fans 13 and 14 are located at downstream side of theheat rollers 11 and 12. The film 20 which moves out of the gap betweenthe heat rollers 11 and 12 is rapidly cooled by fans 13 and 14 to atemperature below the glass transition temperature T_(g). The purpose ofthe provision of the fans 13 and 14 is to cool the film 20 at leastbelow the shape providing temperature To immediately after the film 20is stretched. Thus, it is prevented that a shape is unintentionallygiven to the film 20 after the stretching.

[0028] The punching roller pair 50 is disposed so that the film 20discharged from the stretching roller pair 10 is fed into the punchingroller pair 50. The needle roller 51 is provided with needles plantedthroughout the outer surface thereof. The needle 55 is long enough topenetrate the film 20. The film 20 is fed in a gap between the needleroller 51 and the platen roller 52. The needle roller 51 and the platenroller 52 respectively have built-in heaters 51 a and 52 a and areheated at 70° C., which is higher than the glass transition temperatureT_(g) of the shape memory resin. The film 20 is heated so that the film20 exhibits a rubber state (that is, an elastic state). In this state,the film 20 is pressed by the needle roller 51 and the platen roller 52.

[0029] The needles 55 planted on the outer surface of the needle roller50 pierce the film 20 (which is in the rubber state), so that thethrough-holes 25 are punched in the film 20 by the needles 55. Since theaxial length of the needle roller 50 (covered by the needles 55) is thesame as the width of the film 20, the through-holes 25 are formedthroughout the surface of the film 20. The needle 55 is of a diameterthat permits the through-hole 25 to substantially close after formation.Since the film 20 is in an elastic state, just after the needle 55 movesout of the through-hole 25, the through-hole 25 is contracted andsubstantially closed due to the elastic force.

[0030] The film 20 which moves out of the punching roller pair 50 iscooled by surrounding atmosphere, to a temperature below the glasstransition temperature T_(g) of the shape memory resin. With this, thefilm 20 with through-hole 25 is produced.

[0031] According to the above-described embodiment, the stretching ofthe film 20 and the punching of the through-holes 25 are performed bysubstantially one process shown in FIG. 2. Thus, the whole process issimplified. Further, since the stretching of the film 20 and thepunching of the through-holes 25 are performed by substantially oneapparatus shown in FIG. 2, the equipment for producing the film withthrough-holes is simplified.

[0032] In the above-described producing method, if the punching rollerpair 50 is sufficiently apart from the stretching roller pair 10 so thatthe temperature of the film 20 (at the punching roller pair 50) iscooled by an atmosphere to a temperature at least below the shapeproviding temperature T₀, it is not necessary to provide the fans 13 and14. Conversely, in case the fans 13 and 14 are provided between thestretching roller pair 10 and the punching roller pair S0 as shown inFIG. 2, the distance between the stretching roller pair 10 and thepunching roller pair 50 can be minimized.

[0033] In the above-described embodiment, it is possible to form thethrough-holes 25 so that the through-holes 25 are inclines with respectto the thickness of the film 20. In such case, the needles 55 areprovided to the needle roller 51 so that the needles 55 are inclinedwith respect to the outer surface of the needle roller 50. Further, theneedle 55 of the needle roller 51 can be replaced with projections.

[0034] Further, in a modification of the above-described embodiment, thefilm 20 is made of a plastic such as polytetrafluoroethylene (Teflon(trademark)). In such case, the temperatures of the stretching rollerpair 10 and the punching roller pair 50 are determined according to theheating characteristic of the plastic.

[0035] An ink transfer printer using the film 20 is described. FIG. 4 isa sectional view of the ink transfer printer. The ink transfer printerincludes a thermal line head 3 having multiple of heating elements 35arranged in a row. The above-described film 20 with through-holes (notshown in FIG. 3) is supported by a board 3 a of the thermal line head 3via a spacer 8 provided therebetween, so that the film 20 and thethermal line head 3 are faced with each other.

[0036] The spacer 8 and the board 3 a of the thermal line head 3 aremade of materials which do not allow the permeation of ink. Thus, ink isstored in a space surrounded by the spacer 8, the board 3 a of thethermal line head 3 and the film 20. A platen roller 4 is provided atthe opposing side of the film 20 with respect to the thermal line head3, so that a recording media R is sandwiched by the platen roller 4 andthe film 20. The circumferential surface of the platen roller 4 is madeof rubber. The rotation shaft 4 a of the platen roller 4 is orientatedin a direction in which the heating elements 35 of the thermal line head3 are arranged. When the platen roller 4 is rotated, the recording mediaR is fed in the direction shown by an arrow in FIG. 4, due to a tractionbetween the recording media R and platen roller 4.

[0037]FIG. 5 is an exploded perspective view of the ink transfer printerexcept the platen roller 4. The spacer 8 is a thin plate member whichsurrounds the heating elements 35 of the thermal line head 3. That is,the spacer 8 defines four side borders of the ink space 1 in which theheating elements 35 are located. In order to supply ink to the ink space1, an ink tank 6 is provided on the board 3 a of the thermal line head 3so that the ink tank 6 is adjacent to the spacer 8. The ink tank 6 has anot-shown cavity in which ink can be stored. Ink stored in the ink tank6 is introduced into the ink space 1 through a slit-shaped outletopening 62 formed on the ink tank 6 and a slit-shaped connecting opening85 formed on the spacer 8, due to a capillary action. The film 20 isattached to the upper surface of the spacer 8 so that the through-holes25 are faced with the heating elements 35 of the thermal line head 3.

[0038]FIGS. 6A and 6B are schematic views showing an ink transferringprocess. As shown in FIG. 6A, the diameters of the through-holes 25 aresmall so that ink does not permeate the through-holes 25. The film 20 isalmost in contact with the heating element 35 of the thermal line head3. When the heating element 35 is heated, ink located in the vicinity ofthe heating element 35 is heated. As shown in FIG. 6B, the heated ink isvaporized and expanded, causing an increase in the local pressure ofink. Also, a portion of the film 20 located in the vicinity of theheating element 35 is heated. The elastic coefficient of the heatedportion of the film 20 decreases, so that the heated portion of the film20 is easily deformed. Due to the increase in the local pressure in ink,ink is pushed into the through-hole 25 of the film 20. Further, thethrough-hole 25 is widen so as to allow the permeation of ink. Withthis, ink permeates the through-hole 25 and is transferred onto therecording media R (FIG. 4) which is in contact with the upper surface ofthe film 20. After the heating of the heating elements 35 is stopped,the heated ink is cooled by the surrounding ink, so that the increase inthe local pressure in ink disappears. Further, the heated portion of thefilm is also cooled by ink. With this, the widened through-holes 25recover their original diameters so that the through-holes 25 do notallow the permeation of ink.

[0039] As constructed above, by controlling the thermal line head 3 toselectively heat the heating elements 35 and by rotating the platenroller 4 to feed the recording media R, a desired image is formed on therecording media R.

[0040] In the above-described ink transfer printer, if the glasstransition temperature T_(g) of the film 20 is too high, an energyconsumption of the ink transfer printer may increase. Conversely, if theglass transition temperature T_(g) of the film 20 is too low, thethrough-holes 25 may unintentionally open when the temperature of theenvironment of the printer, particularly in summer. Thus, it ispreferable that the glass transition temperature T_(g) of the film 20 isfrom 50 to 80° C. (as long as the heating temperature of the punchingroller pair 50 shown in FIG. 2 is set to a temperature higher than theglass transition temperature T_(g) of the film 20).

[0041] Although the producing apparatus and producing method of a filmwith through-holes are described herein with respect to the preferredembodiment, many modifications and changes can be made without departingfrom the spirit and scope of the invention.

[0042] The present disclosure relates to subject matters contained inJapanese Patent Application No. HEI 09-293484, filed on Oct. 9, 1997,which is expressly incorporated herein by reference in its entirety.

What is claimed is:
 1. A method for producing a film with through-holesusing a film producing apparatus comprising: a pair of stretchingrollers which sandwich a film therebetween and stretch said film in atleast one direction; and a pair of punching rollers at least one ofwhich has projections formed on an outer surface thereof, which sandwichsaid film therebetween and punch through-holes in said film; and saidstretching rollers and said punching rollers are disposed so that saidfilm stretched by said stretching rollers are fed to said punchingrollers; said method comprising: stretching said film by means of saidstretching rollers; and punching through-holes in said film.
 2. Themethod according to claim 1 , wherein said film is made of shape memoryresin.
 3. The method according to claim 2 , wherein in said stretching,said film is heated to a temperature above a shape providing temperatureof said shape memory resin.
 4. The method according to claim 2 , whereinin said punching, said film is heated to a temperature above a glasstransition temperature of said shape memory resin.
 5. The methodaccording to claim 2 , further comprising cooling said film below ashape providing temperature of said shape memory resin, after saidstretching.
 6. The method according to claim 1 , wherein said glasstransition temperature of said shape memory resin is below said shapeproviding temperature, and wherein said punching comprises: punchingthrough-holes in said unpunched shape memory resin film while heatingsaid shape memory resin film to a temperature above a glass transitiontemperature but below said shape providing temperature of said shapememory resin.